The present embodiments relate to a device and a method for localized attenuation of a high-frequency field of a magnetic resonance tomography system.
Magnetic resonance devices for examining objects or patients using magnetic resonance tomography (e.g., MR, MRT, MRI) are known, for example, from DE10314215B4.
In application DE 10 2009 033 084.4, a waveguide antenna for a magnetic resonance tomography device is described, the waveguide antenna including a number of metal surfaces and diodes being located between the metal surfaces. The metal surfaces are connected to one another via the diodes for HF signals when the diodes are switched on between the metal surfaces. The metal surfaces are unconnected to one another for HF signals when the diodes are switched off between the metal surfaces.
Magnetic resonance systems (e.g., MRI or MRT) may work with a number of different antennas for emitting high-frequency pulses for nuclear resonance excitation and/or for receiving induced magnetic resonance signals. A magnetic resonance system may have one larger body coil that may be fixedly mounted in the device, as well as several small local coils. In contrast to a body coil, local coils are used to record detailed images of body parts or organs of a patient that are located comparatively close to the body surface or local coil. The control system for the coils of an MRT may also be the transmitting system of the MRT.
A publication by Pruessmann et al. describes an antenna for UHF-MRI that is based on the principle of wave propagation in waveguides, where use is made of the effect that a metal tube, as formed in an MR system (e.g., by an HF screen present by default or an inner metal wall of the magnet), functions as a waveguide as of a particular cut-off frequency. The cut-off frequency may be exceeded in the case of MRT systems.